U.S. patent number 6,157,449 [Application Number 09/174,986] was granted by the patent office on 2000-12-05 for depolarized light scattering array apparatus and method of using same.
This patent grant is currently assigned to Symyx Technologies. Invention is credited to Damian A. Hajduk.
United States Patent |
6,157,449 |
Hajduk |
December 5, 2000 |
Depolarized light scattering array apparatus and method of using
same
Abstract
A method and apparatus for characterizing and scanning an array
of material samples in a combinatorial library in parallel is
disclosed. The apparatus includes a sample block having a plurality
of regions for containing the material samples, a polarized light
source to illuminate the materials, an analyzer having a
polarization direction oriented 90.degree. relative to the
polarization direction of the polarized light source so as to
filter out light intensities having the same polarization direction
as the incident light beams from the light source after
illuminating the material samples, and a detector for analyzing
changes in the intensity of the light beams. In one aspect, the
light source in combination with a polarizer, includes a plurality
of light beams to simultaneously illuminate the entire array of
materials with linearly polarized light such that the
characterization can be performed quickly. In another aspect, the
materials in the sample block are subjected to different
environmental conditions wherein the detector analyzes the array as
a function of those environmental conditions.
Inventors: |
Hajduk; Damian A. (San Jose,
CA) |
Assignee: |
Symyx Technologies (Santa
Clara, CA)
|
Family
ID: |
22638347 |
Appl.
No.: |
09/174,986 |
Filed: |
October 19, 1998 |
Current U.S.
Class: |
356/367; 356/364;
356/365; 356/491; 356/936 |
Current CPC
Class: |
G01N
21/21 (20130101); B01J 2219/00286 (20130101); B01J
2219/00315 (20130101); B01J 2219/00585 (20130101); B01J
2219/00659 (20130101); B01J 2219/00707 (20130101); B01J
2219/0072 (20130101); B01J 2219/00745 (20130101); C40B
40/18 (20130101); C40B 60/14 (20130101); G01J
4/04 (20130101); G01N 2201/0813 (20130101) |
Current International
Class: |
G01N
21/21 (20060101); G01J 4/00 (20060101); G01J
4/04 (20060101); G01J 004/00 () |
Field of
Search: |
;356/367,365,364,345,346,351,445,368 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
5257092 |
October 1993 |
Noguchi et al. |
5694205 |
December 1997 |
Gualtieri et al. |
5788632 |
August 1998 |
Pezzaniti et al. |
6031614 |
February 2000 |
Michaelis et al. |
|
Foreign Patent Documents
|
|
|
|
|
|
|
PCT/US97/18521 |
|
Oct 1997 |
|
WO |
|
Primary Examiner: Font; Frank G.
Assistant Examiner: Punnoose; Roy M.
Claims
What is claimed is:
1. An apparatus for characterizing an array of material samples in
a library, comprising:
a sample block adapted to receive a plurality of material samples
to be characterized at predefined regions on said sample block;
a light source for providing at least one linearly polarized light
beam of a predetermined wavelength, said light source being
positioned on a first side of said sample block such that said
light beam may be directed to pass through at least one region and
said material sample contained therein;
an analyzer positioned on a second side of said sample block, said
analyzer having a predetermined polarization direction different
than said polarization direction of said linearly polarized light
beam; and
a detector for outputting a signal corresponding to a detected
intensity of said light beam passing through said at least one
material sample and said analyzer, said detector located adjacent
said analyzer such that said analyzer is positioned between said
detector and said sample block.
2. The apparatus of claim 1, further including an optical filter to
convert said linearly polarized light beam into circularly
polarized light, said optical filter being positioned on said first
side of said sample block between said light source and said sample
block.
3. The apparatus of claim 1, further including a collimator to
collimate said polarized light beam, said collimator being
positioned on a second side of said sample block between said
sample block and said analyzer.
4. The apparatus of claim 1, further including a temperature
controlled block having a plurality of holes through which said
polarized light beams may pass, said sample block being positioned
in said temperature controlled block such that said light beams are
directed to pass through said holes and through said predefined
regions to said material samples.
5. The apparatus of claim 4, wherein the temperature of said
temperature controlled block is varied by predetermined amounts by
at least one resistance heater or a thermoelectric device.
6. The apparatus of claim 5, wherein the temperature of said
temperature controlled block is monitored by a thermocouple,
thermistor, or resistive thermal device.
7. The apparatus of claim 6, wherein a signal is outputted by said
thermocouple, thermistor or resistive thermal device to an external
processor, said external processor supplying power to said heater
or said thermoelectric device in predetermined amounts so as to
control the temperature of said temperature controlled block.
8. The apparatus of claim 4, wherein said temperature controlled
block includes a plurality of passages formed therein, said
passages receiving a temperature control agent to vary the
temperature of said temperature controlled black by predetermined
amounts.
9. The apparatus of claim 8, wherein said temperature control agent
is water, silicone oil or fluorinated solvent.
10. The apparatus of claim 4, wherein said outputted signal
corresponds to said intensity of said light beam as a function of
temperature.
11. The apparatus of claim 1, further including a support plate for
supporting said light source and a polarizer, wherein said
polarizer is positioned between said light source and said sample
block to provide said at least one linearly polarized light beam,
said analyzer said predetermined polarization direction of said
analyzer being different than a polarization direction of said
polarizer.
12. The apparatus of claim 11, wherein said polarization direction
of said analyzer is oriented 90 degrees with respect to said
polarization direction of said polarizer.
13. The apparatus of claim 11, wherein said light source includes a
plurality of individual light sources that are inserted into an
array of corresponding apertures disposed in said support plate,
said individual light sources simultaneously producing a plurality
of light beams.
14. The apparatus of claim 13, wherein said detector simultaneously
outputs a signal that corresponds to said detected intensity of all
of said linearly polarized light beams passing through each
material disposed in of said predefined regions and passing through
said analyzer.
15. The apparatus of claim 14, further including an imaging system
having a fiber optic system positioned adjacent to said analyzer to
capture said light beams passing through said analyzer, said fiber
optic system being in communication with said detector.
16. The apparatus of claim 15, wherein said fiber optic system
includes: a first fiber optic plate positioned adjacent said
analyzer, said first fiber optic plate having a first array of
apertures arranged a predetermined distance apart so as to be in
substantial alignment with said array of regions; and a second
fiber optic plate positioned adjacent said first fiber optic plate,
said second fiber optic plate having a second array of apertures
arranged a predetermined distance apart such that said apertures in
said second array are closely packed together relative to said
first array of apertures of said first fiber optic plate, wherein
said first fiber optic plate and said second fiber optic plate are
connected together at said first and second arrays of apertures by
a fiber optic bundle.
17. The apparatus of claim 1, wherein said outputted signal
corresponds to said intensity of said light beam as a function of
time.
18. The apparatus of claim 1, further including an environmental
chamber having optically transparent windows to permit the passage
of said light beam, wherein said sample block is mounted within
said environmental chamber.
19. The apparatus of claim 18, wherein said environmental chamber
is pressurized by at least one gas.
20. The apparatus of claim 19, wherein said environmental chamber
further includes a pressure sensor for monitoring pressure in said
environmental chamber, a regulator valve for controlling the
pressure of said environmental chamber, and a processor for
monitoring signals from said pressure sensor and for controlling
the regulator valve so as to maintain the desired pressure inside
said environmental chamber based on the signals received from said
pressure sensor.
21. The apparatus of claim 20, wherein said outputted signal
corresponds to said intensity of said light beam as a function of
pressure.
22. The apparatus of claim 20, wherein said outputted signal
corresponds to said intensity of said light beams as a function of
time at a given pressure.
23. The apparatus of claim 18, wherein said environmental chamber
is continuously filled with a mixture of two or more gases.
24. The apparatus of claim 23, wherein amounts of each of said
gases are controlled by regulator valves.
25. The apparatus of claim 23, wherein said environmental chamber
further includes a vent valve, wherein said vent valve continuously
permits a predetermined amount of said mixture to be vented from
said environmental chamber.
26. The apparatus of claim 23, wherein said outputted signal
corresponds to said intensity of said light beam as a function of
gas composition.
27. The apparatus of claim 23, wherein said outputted signal
corresponds to said intensity of said light beams as a function of
time at a given gas composition.
28. The apparatus of claim 1, wherein said sample block further
includes pairs of electrodes embedded therein, wherein each pair of
said electrodes is arranged in an opposing manner with one of said
regions disposed therebetween.
29. The apparatus of claim 28, wherein each pair of electrodes are
connected in parallel to a power supply such that application of a
voltage across said pair generates an electric field extending
across each of said regions.
30. The apparatus of claim 29, wherein said outputted signal
corresponds to said intensity of said light beams as a function of
applied voltage.
31. The apparatus of claim 29, wherein said outputted signal
corresponds to said intensity of said light beams as a function of
time after a given voltage is applied.
32. The apparatus of claim 29, wherein said outputted signal
corresponds to said intensity of said light beams as a function of
time after a given voltage is removed.
33. The apparatus of claim 1, wherein said sample block further
includes pairs of solenoid devices embedded therein, wherein each
of said pairs of solenoid devices are arranged in an opposing
manner with a region disposed therebetween, so as to create a
magnetic field extending across each of said regions.
34. The apparatus of claim 33, wherein said solenoid devices
include circular coils wrapped around a solid metal core, wherein
said coils are electrically connected to a power supply such that
application of current across each of said circular coils generates
said magnetic field extending across each of said regions.
35. The apparatus of claim 33, wherein said outputted signal
corresponds to said detected intensity of said light beam as a
function of magnetic field strength.
36. The apparatus of claim 33, wherein said outputted signal
corresponds to said detected intensity of said light beam as a
function of time after said magnetic field is applied.
37. The apparatus of claim 33, wherein said outputted signal
corresponds to said intensity of said light beams as a function of
time after said magnetic field is removed.
38. The apparatus of claim 1, further including a pair of circular
wire coils connected to a power supply, wherein said wire coils are
positioned adjacent to said apparatus in an opposing manner such
that said apparatus is disposed therebetween so as to generate a
uniform magnetic field over said apparatus.
39. The apparatus of claim 38, wherein said outputting signal
corresponds to said detected intensity of said light beam as a
function of magnetic field strength.
40. The apparatus of claim 38, wherein said outputted signal
corresponds to said detected intensity of said light beam as a
function of time after said magnetic field is applied.
41. The apparatus of claim 38, wherein said out putted signal
corresponds to said detected intensity of said light beam as a
function of time after said magnetic field is removed.
42. An apparatus for characterizing an array of material samples,
comprising;
a light source for providing at least one light beam, said light
source being positioned in a support plate;
a polarizer having a predetermined polarization direction, said
polarizer positioned adjacent to said light source such that said
light beam may be directed through said polarizer to produce a
linearly polarized light beam;
a temperature controlled block having a well with plurality of
holes therethrough, said well adapted to receive a sample block
having an array of predefined regions therein for containing the
array of material samples, said linearly polarized light beam being
directed through at least one of said holes of said well to pass
through at least one of said regions in said sample block such that
said linearly polarized light beam is directed at least one
material sample;
an analyzer positioned adjacent said temperature controlled block
on a side opposite of said polarizer, said analyzer having a
predetermined polarization direction that is different than a
polarization direction of said polarizer; and
a detector for outputting a signal corresponding to an intensity of
said polarized light beam passing through said at least one
material sample and said analyzer, said detector being located
adjacent said analyzer on a side opposite said temperature
controlled block such that said analyzer is positioned between said
detector and said temperature controlled block.
43. The apparatus of claim 42, further including a collimator to
collimate said polarized light beam, said collimator being
positioned adjacent said temperature controlled block on a side
opposite of said polarizer such that said collimator is positioned
between said temperature controlled block and said analyzer.
44. The apparatus of claim 42, further including an optical filter
to convert said linearly polarized light beam into a circularly
polarized light beam, said optical filter being positioned on a
first side of said temperature controlled block between said
polarizer and said temperature controlled block.
45. The apparatus of claim 42, wherein the temperature of said
temperature controlled block is varied by predetermined amounts by
at least one resistance heater or a thermoelectric device.
46. The apparatus of claim 42, wherein said temperature controlled
block includes a plurality of passages formed therein, said
passages receiving a temperature control agent to vary the
temperature of said temperature controlled block by predetermined
amounts.
47. The apparatus of claim 46, wherein said temperature controlled
block further includes resistance heaters or thermoelectric
devices, such that said temperature agent and said resistance
heaters or thermoelectric devices, in combination, serve to vary
the temperature of said temperature controlled block by
predetermined amounts.
48. The apparatus of claim 46, wherein said resistance heaters or
thermoelectric devices are monitored by a thermocouple, a
thermistor or resistive thermal device, said thermocouple,
thermistor or resistive thermal device outputting a signal to an
external processor which supplies power to said resistance heaters
or thermoelectric devices in varying predetermined amounts so as to
control the temperature of said temperature controlled block.
49. The apparatus of claim 42, wherein said polarization of said
analyzer is oriented 90 degrees with respect to said predetermined
polarization direction of said polarizer.
50. The apparatus of claim 42, wherein said light source produces a
plurality of individual light beams that simultaneously illuminate
all of said material samples of said array, and wherein said
detector simultaneously outputs a signal corresponding to the
detected intensity of said polarized light beams passing through
each of said material samples and said analyzer.
51. The apparatus of claim 50 wherein said detector includes a
fiber optic system to simultaneously capture said detected
intensity of said plurality of light beams, said fiber optic system
being positioned adjacent said analyzer and in communication with a
charge-coupled device.
52. The apparatus of claim 50, wherein said outputted signal
corresponds to said detected intensity of said polarized light
beams as a function of time.
53. The apparatus of claim 50, wherein said outputted signal
corresponds to said detected intensity of said polarized light
beams as a function of temperature.
54. An apparatus for characterizing an array of material samples,
comprising;
a light source providing at least one light beam, said light source
being positioned in a support plate;
a polarizer having a predetermined polarization direction, said
polarizer positioned adjacent to said light source such that said
at least one light beam is directed through said first sheet of
said polarizer to produce a linearly polarized light beam;
a substantially gas-tight environmental chamber having optically
transparent windows to permit the passage of said linearly
polarized light beam, wherein a sample block is mounted within said
environmental chamber, said sample block having an array of
predetermined regions therein for containing the array of material
samples to be characterized, said linearly polarized light beam
being directed through said windows and at least one region to
illuminate at least one material sample;
an analyzer positioned adjacent to said environmental chamber on a
side opposite of said polarizer, said analyzer having a
polarization that is different than said predetermined polarization
of said polarizer; and
a detector for outputting a signal corresponding to a detected
intensity of said polarized light beam passing through said at
least one material sample and said analyzer, said detector located
adjacent said analyzer on a side opposite said environmental
chamber such that said analyzer is positioned between said detector
and said environmental chamber.
55. The apparatus of claim 54, wherein said environmental chamber
is pressurized by at least one gas.
56. The apparatus of claim 54, wherein said environmental chamber
is continuously filled with a mixture of at least two gases.
57. The apparatus of claim 56, wherein said environmental chamber
further includes a vent valve, wherein said vent valve continuously
permits a predetermined amount of said mixture to be vented from
said environmental chamber.
58. The apparatus of claim 54, further including a collimator to
collimate said polarized light beam, said collimator being
positioned adjacent said environmental chamber on a side opposite
said polarizer such that said collimator is positioned between said
environmental chamber and said analyzer.
59. The apparatus of claim 54, further including an optical filter
to convert said linearly polarized light beam into circularly
polarized light, said optical filter being positioned on a first
side of said environmental chamber between said polarizer and said
environmental chamber.
60. The apparatus of claim 54, wherein said light source is a
plurality of individual light sources that are inserted into an
array of corresponding apertures disposed in said support plate,
wherein said individual light sources simultaneously illuminate the
array of material samples, and wherein said detector outputs a
signal corresponding to said detected intensity of said polarized
light beams passing through each of said material samples contained
in said regions of said sample block and said analyzer.
61. The apparatus of claim 54, wherein said detector includes a
fiber optic system to simultaneously capture said intensity of said
plurality of light beams, wherein said fiber optic system
includes:
a first fiber optic plate positioned adjacent to said analyzer,
said first fiber optic plate having a first array of apertures
arranged a predetermined distance apart so as to be in substantial
alignment with said regions; and
a second fiber optic plate having a second array of apertures
arranged a predetermined distance apart such that said apertures in
said second array are closely packed together relative to said
first array of apertures of said first fiber optic plate, wherein
said first fiber optic plate and said second fiber optic plate are
connected together by a fiber optic bundle.
62. An apparatus for characterizing an array of materials,
comprising;
a light source for providing at least one light beam, said light
source being positioned in a support plate;
a polarizer having a predetermined polarization direction, said
polarizer positioned adjacent to said light source such that said
light beam may be directed through said polarizer to produce a
linearly polarized light beam;
a sample block having predefined regions for containing said array
of material samples, wherein said sample block further includes
pairs of solenoid devices embedded therein, wherein each of said
pairs of solenoid devices are arranged in an opposing manner with
one of said predefined regions disposed therebetween;
an analyzer positioned adjacent to said sample block on a side
opposite of said polarizer, said analyzer having a polarization
direction that is different than said predetermined polarization
direction of said polarizer; and
a detector for outputting a signal corresponding to a detected
intensity of said polarized light beam passing through said at
least one material sample contained in at least one region and said
analyzer, said detector being located adjacent said analyzer on a
side opposite said sample block such that said analyzer is
positioned between said detector and said sample block.
63. The apparatus of claim 62, wherein said solenoid devices
include circular coils wrapped around a solid metal core, wherein
said coils are electrically connected to a power supply such that
application of current across each of said circular coils generates
a magnetic field extending across each of said regions.
64. The apparatus of claim 62, further including a collimator to
collimate said polarized light beam, said collimator being
positioned adjacent said sample block on a side opposite said
polarizer such that said collimator is positioned between said
sample block and said analyzer.
65. The apparatus of claim 62, wherein said light source is a
plurality of individual light sources that are inserted into an
array of corresponding apertures disposed in said support plate,
wherein said individual light sources simultaneously illuminate the
array of materials, and wherein said detector outputs a signal
corresponding to said detected intensity of said polarized light
beams passing through each of material samples contained in said
regions of said sample block and said analyzer.
66. The apparatus of claim 62, wherein said detector includes a
fiber optic system to simultaneously detect said intensity of said
plurality of light beams, wherein said fiber optic system
includes:
a first fiber optic plate positioned adjacent to said analyzer,
said first fiber optic plate having a first array of apertures
arranged a predetermined distance apart so as to be in substantial
alignment with said array of regions; and
a second fiber optic plate having a second array of apertures
arranged a predetermined distance apart such that said apertures in
said second array are closely packed together relative to said
first array of apertures of said first fiber optic plate, wherein
said first fiber optic plate and said second fiber optic plate are
connected together by a fiber optic bundle.
67. The apparatus of claim 62, further including an optical filter
to convert said linearly polarized light beam into circularly
polarized light, said optical filter being positioned on said first
side of said sample block between said polarizer and said sample
block.
68. An apparatus for characterizing an array of material samples,
comprising:
a light source for providing at least one light beam, said light
source being positioned in a support plate;
a polarizer having a predetermined polarization direction, said
polarizer positioned adjacent to said light source such that said
light beam may be directed through said polarizer to produce a
linearly polarized light beam;
a sample block having predefined regions therein for containing
said array of material samples in said sample block, wherein said
sample block further includes pairs of electrodes embedded therein,
wherein each of said pairs of electrodes are arranged in an
opposing manner with one of said regions disposed therebetween;
an analyzer positioned adjacent to said sample block on a side
opposite of said polarizer, said analyzer having a polarization
direction that is different than said predetermined polarization
direction of said polarizer; and
a detector for outputting a signal corresponding to a detected
intensity of said polarized light beam passing through said at
least one material sample contained in at least one of said
predefined regions and said analyzer, said detector being located
adjacent said analyzer on a side opposite said sample block such
that said analyzer is positioned between said detector and said
sample block.
69. The apparatus of claim 68, wherein said pairs of electrodes are
connected in parallel to a power supply, such that application of a
voltage across said pairs generates an electric field extending
across each of said regions.
70. The apparatus of claim 68, further including a collimator to
collimate said polarized light beam, said collimator being
positioned adjacent said sample block on a side opposite said
polarizer such that said collimator is positioned between said
sample block and said analyzer.
71. The apparatus of claim 68, further including an optical filter
to convert said linearly polarized light beam into circularly
polarized light, said optical filter being positioned on said first
side of said sample block between said polarizer and said sample
block.
72. The apparatus of claim 68, wherein said light source is a
plurality of individual light sources that are inserted into an
array of corresponding apertures disposed in said support plate,
wherein said individual light sources simultaneously illuminate the
array of material samples, and wherein said detector outputs a
signal corresponding to said detected intensity of said polarized
light beams passing through each of said material samples contained
in said predefined regions of said sample block and said
analyzer.
73. The apparatus of claim 68, wherein said detector includes a
fiber optic system to simultaneously detect said intensity of said
plurality of light beams, wherein said fiber optic system
includes:
a first fiber optic plate positioned adjacent to said analyzer,
said first fiber optic plate having a first array of apertures
arranged a predetermined distance apart so as to be in substantial
alignment with said array of regions; and
a second fiber optic plate having a second array of apertures
arranged a predetermined distance apart such that said apertures in
said second array are closely packed together relative to said
first array of apertures of said first fiber optic plate, wherein
said first fiber optic plate and said second fiber optic plate are
connected together by a fiber optic bundle.
74. An apparatus for characterizing an array of material samples,
comprising:
a light source for providing at least one light beam, said light
source being positioned in a support plate;
a polarizer having a predetermined polarization direction, said
polarizer positioned adjacent to said light source such that said
light beam may be directed through said polarizer to produce a
linearly polarized light beam;
a sample block having predefined region therein for containing said
array of material samples in said sample block;
an analyzer positioned adjacent to said sample block on a side
opposite of said polarizer, said analyzer having a polarization
direction that is different than said predetermined polarization
direction of said polarizer, wherein said light source, polarizer,
sample block and analyzer are connected together as a single
unit;
a detector for outputting a signal corresponding to a detected
intensity of said polarized light beam passing through said at
least one material sample contained in said predefined regions and
said analyzer, said detector located adjacent said analyzer on a
side opposite said sample block such that said sample block is
positioned between said detector and said sample block; and
a pair of circular coils positioned adjacent said single unit in an
opposing manner with said single unit being disposed
therebetween.
75. The apparatus of claim 74, wherein said circular coils are
connected to a power supply, such that application of voltage
across said pair of circular coils generates a uniform magnetic
field across said single unit.
76. The apparatus of claim 75, wherein said single unit further
includes a collimator to collimate said polarized light beam, said
collimator being positioned adjacent said sample block on a side
opposite said polarizer such that said collimator is positioned
between said sample block and said analyzer.
77. The apparatus of claim 75, wherein said single unit further
includes an optical filter being positioned on said first side of
said sample block between said polarizer and said sample block.
78. The apparatus of claim 75, wherein said individual light
sources simultaneously illuminate the array of material samples,
and wherein said detector outputs a signal corresponding to said
detected intensity of said polarized light beams passing through
each of said material samples contained in said predefined regions
of said sample block and said analyzer.
79. The apparatus of claim 75, wherein said unit further includes a
fiber optic system to simultaneously detect said intensity of said
plurality of light beams, wherein said fiber optic system
includes:
a first fiber optic plate positioned adjacent to said analyzer,
said first fiber optic plate having a first array of apertures
arranged a predetermined distance apart so as to be in substantial
alignment with said array of regions; and
a second fiber optic plate having a second array of apertures
arranged a predetermined distance apart such that said apertures in
said second array are closely packed together relative to said
first array of apertures of said first fiber optic plate, wherein
said first fiber optic plate and said second fiber optic plate are
connected together by a fiber optic bundle.
80. A method of characterizing an array of material samples,
comprising the steps of:
providing an array of material samples disposed in regions spaced
apart at a predetermined distance in a sample block containing;
illuminating at least one material sample of said array with at
least one linearly polarized light beam passing through said
region;
passing said linearly polarized light beam that has illuminated
said at least one material sample through an analyzer that has a
polarizing direction that is different than said polarization
direction of said linearly polarized light beam;
detecting changes in intensity of said linearly polarized light
beam after said light beam is passed though said material sample
and said analyzer; and
determining characteristics of said material sample based on said
detected changes in said intensity of said light beam.
81. The method of claim 80, wherein said detecting step is
performed at predefined intervals of time, and wherein said
determining step determines said characteristics as a function of
time.
82. The method of claim 80, further comprising the step of varying
the temperature of said sample block at a predetermined rate;
wherein said determining step determines said characteristics of
said material samples as a function of temperature.
83. The method of claim 80, wherein said step of illuminating
further comprises providing a light beam from a light source and
polarizing said light beam by passing said light beam through a
polarizer.
84. The method of claim 80, wherein said step of detecting further
comprises collecting changes in said detected intensity and
transmitting said changes to an imaging system.
85. The method of claim 80, wherein said step of illuminating
further comprises simultaneously illuminating said array of
material samples with a plurality of linearly polarized light
beams, and wherein said characteristics of each of said material
samples are determined simultaneously.
86. The method of claim 80, further including the step of
collimating said linearly polarized light beam prior to step of
passing said polarized light beam through said analyzer.
87. The method of claim 80, further including the step of
converting said linearly polarized light into circularly polarized
light prior to said illuminating step.
88. The method of claim 80, further comprising the step of
subjecting the array of material samples to pressure by enclosing
said array of materials in a substantially gas-tight environmental
chamber and filling said environmental chamber with at least one
gas.
89. The method of claim 88, wherein said step of pressurizing is
performed at a predefined rate, wherein said determining step
determines said characteristics as a function of pressure.
90. The method of claim 80, further comprising the step of
subjecting the array of material samples to a mixture of two or
more gases.
91. The method of claim 90, wherein said determining step
determines said characteristics of said material sample as a
function of gas composition.
92. The method of claim 80, further comprising the step of
generating an electric field extending across each material sample
disposed in each of said regions.
93. The method of claim 92, wherein said determining step
determines said characteristics of said material sample as a
function of electric field strength.
94. The method of claim 80, further comprising the step of
generating a magnetic field extending across each material sample
disposed in each of said regions.
95. The method of claim 94, wherein said determining step
determines said characteristics of said material sample as a
function of magnetic field strength.
96. The method of claim 80, further comprising the step of
generating a substantially uniform magnetic field extending across
the entire array of material samples.
97. The method of claim 80, wherein said step of detecting further
comprises collecting changes in said intensity and transmitting
said changes to a charge-coupled device.
98. The method of claim 80, wherein said providing step further
requires that said array of material samples is composed of at
least 10 material samples.
99. The method of claim 80, wherein said providing step further
requires that said array of material samples is composed of at
least 50 material samples.
100. The method of claim 80, wherein said providing step further
requires that said array of material samples is composed of at
least 100 material samples.
101. The method in claim 80, wherein the rates of said detecting
step and determining steps equal a rate that is equal to or less
than one minute per sample.
102. The method in claim 80, wherein detecting and determining
steps are each performed at rates equal to or less than one minute
per sample.
Description
BACKGROUND
1. Technical Field
The present invention relates to a method and apparatus for rapidly
screening and characterizing an array of materials. More
particularly, this invention is directed to an optical technique
for the parallel screening and characterizing of different
materials in a combinatorial library.
2. Discussion
Combinatorial materials science refers generally to methods for
creating a collection of chemically diverse materials or compounds
and to methods for rapidly testing or screening such collections,
commonly known as libraries, for desirable performance
characteristics and properties. In recent years, the advent of
combinatorial chemistry has revolutionized the process of drug
discovery (see for example 29 Acc. Chem. Res. 1-170 (1996); 97
Chem. Rev. 349-509 (1997); S. Borman, Chem. Eng. News 43-62 (Feb.
24, 1997); A. M. Thayer, Chem. Eng. News 57-64 (Feb. 12, 1996); N.
Terret, 1 Drug Discovery Today 402 (1996)). Researchers have also
used combinatorial strategies in the discovery and optimization of
materials, such as superconductors, zeolites, magnetic materials,
phosphors, catalysts, thermoelectric materials, high and low
dielectric materials and the like.
Although new and useful materials can be developed in less time
using combinatorial methods, further efficiency gains can be
achieved by improving the speed and efficiency of library
screening. Once a combinatorial library is created, there looms the
daunting task of identifying a handful of promising compounds or
materials out of a combinatorial library comprising hundreds,
thousands or perhaps millions of compounds or materials. While the
use of combinatorial methods in synthesizing candidate compounds or
materials speeds up the discovery process, testing the individual
compounds or materials can consume a significant amount of time and
resources.
Known analytical techniques are often unsuitable for screening
combinatorial libraries because of poor sensitivities, slow
response and the inherently serial nature of most instrumentation.
The latter two difficulties can be overcome by adopting parallel
measurement techniques, in which the same characterization method
is applied to all elements in the library simultaneously. However,
the ease with which this can be accomplished is strongly dependent
on the specific nature of the technique utilized. Optically based
methods possess a clear advantage in this regard in that parallel
data collection and analysis is easily accomplished using
preexisting imaging and image processing technologies. The optical
characteristics of a compound or material reflect the electronic
properties of the constituent molecules as well as the arrangement
of these molecules in space, making it possible to detect changes
in physical or chemical structure through optical means. One known
application of such a method has been applied to screening selected
characteristics of materials as a function of applied voltage
(described in co-pending U.S. patent application Ser. No.
08/947,085 "Optical Systems and Methods for Rapid Screening of
Libraries of Different Materials", published as WO 98/15805, which
is incorporated herein by reference).
However, there exists a need for other apparatuses and methods for
rapidly screening and characterizing, in parallel, the optical and
physical properties of an array of compounds or materials.
SUMMARY
In accordance with the present invention, there is provided an
apparatus for screening an array of at least partially transparent
material samples in a combinatorial library, wherein the material
samples exhibit changes in birefringence as a function of
environmental conditions. The apparatus includes a sample block
having a plurality of regions therein for receiving the library
members. The term sample block is not meant to place any structural
limitations (e.g. size or shape) on the invention. The apparatus
also includes a light source that provides at least one light beam
light that is polarized and directed toward the regions, an
analyzer for filtering out light having the same polarization as
the incident light beam after it passes through the regions, and a
detector for analyzing changes in the intensity of the light beams
due to the optical characteristics of the library members. The
sample block, light source, analyzer and detector are all arranged
in series.
Preferably, the sample block receives vials of the material samples
within the regions formed therein. The vials that receive the
library members can be constructed from any material or combination
of materials which are at least partially transparent to the light
emitted by the source. Suitable materials include glass, quartz,
and transparent plastic sheets which are generally free of residual
stresses. These vials should be nonbirefringent, in that, they
should not alter the polarization characteristics of light which
passes through them.
In accordance with one aspect of the invention, the light source
preferably includes a plurality of lights, such as light emitting
diodes (LEDs), that are all directed toward the regions
simultaneously such that the entire array of material samples may
be illuminated at once. A polarizer, such as a commercially
available polarizing filter or polarizing mirror, is placed between
the light source and the regions to polarize the light before it
passes through the vials and material samples in the library. The
polarized light beams are then collimated, preferably by passing
the light beams through a separate collimator plate, to reduce
stray light. Passage through the material sample alters the
polarization of the light in a manner determined by the structural
characteristics of the material sample. Next, the light beams are
passed through a second polarizer, i.e., an analyzer, wherein the
second polarizer has a preferred polarization direction oriented at
90.degree. relative to the first polarizer. The analyzer serves to
filter the light beams, only transmitting that fraction of the
radiation which has a specific linear polarization.
In accordance with another aspect of the invention, the detector
includes a fiber optic assembly and a charged coupled device (CCD)
camera to capture readings of the light intensity transmitted
through the material samples. A first fiber optic plate is
positioned above the second polarizer and a second fiber optic
plate is placed above the first fiber optic plate. A bundle of
fiber optics is placed between the plates with the ends of the
fibers extending through holes in both plates. Light transmitted
through the second polarizer is captured by the fiber ends
extending through the first plate and transmitted through the
fibers to emerge at the second plate. The fibers in the bundle are
arranged in a tapered configuration so as to reduce the dimensions
of the area over which the light is distributed from the array of
samples to a size more easily imaged by the CCD camera.
In accordance with another aspect of the invention, the apparatus
may also include a temperature controlled block. The sample block
holding the vials of material samples is disposed within the
temperature controlled block such that intensity readings of the
material samples may be evaluated as a function of temperature. The
apparatus may further include a substantially gas-tight
environmental chamber. The sample block holding the vials of
material samples is mounted within the substantially gas-tight
environmental chamber and at least one gas is directed into the
chamber so as to subject the material samples to pressure, wherein
intensity readings of the material samples may be evaluated as a
function of pressure. Alternatively, the substantially gas-tight
environmental chamber may be subject to a continuous mixture of two
or more gases such that intensity reading of the material samples
may be evaluated as a function of the gas mixture composition.
In accordance with another aspect of the invention, the sample
block may further include an array of electrode pairs, wherein a
separate electrode pair is associated with each region. The
electrode pairs are arranged in an opposing manner with the region
containing the materials disposed there between. A power supply is
connected in series with the electrode pairs such that when voltage
is applied to the pairs, an electric field is generated across each
material sample. The intensity readings of the material samples may
then be evaluated as a function of applied voltage.
In accordance with another aspect of the invention, the sample
block may further include pairs of electromagnetic devices, wherein
a separate electromagnetic device pair is associated with one
region. The pairs of electromagnetic devices are arranged in an
opposing manner with the region disposed therebetween. A power
supply is connected in series with the pairs of electromagnetic
devices such that when voltage is applied, a magnetic field is
generated across each material sample. The intensity readings of
the material samples may then be evaluated as a function of
magnetic field strength.
In accordance with another aspect of the invention, there is
provided a method of characterizing an array of material samples of
a combinatorial library comprising the steps of providing an array
of material samples in transparent sample blocks, e.g. in vials,
illuminating at least one material in the array with a beam of
polarized light that passes through the vials, filtering out
intensity of the polarized light beam that has the same
polarization direction as the incident light beam by passing the
polarized light beam through an analyzer having a polarization
direction oriented at a predetermined angle, (e.g. without
limitation, 90.degree. with respect to the direction of the
polarized light beam), detecting changes in the intensity of the
polarized light beam due to the optical characteristics of the
material sample and determining characteristics of at least one
material based on the detected changes in the intensity values. In
the preferred method, a plurality of polarized light beams are
provided such that the entire array of material samples is
illuminated simultaneously.
In accordance with another aspect of the invention, the method may
further include determining characteristics of the material samples
as a function of various environmental conditions. In one
embodiment, the temperature of the material samples is varied such
that the detecting and determining steps are performed as a
function of temperature. In another embodiment the materials are
subject to pressure such that the detecting and determining step
are performed as a function of pressure. The material sample may
also be continuously subjected to a mixture of gases such that the
detecting step may be done as a function of gas composition.
Further, the method also may include generating an electric field
across each material samples such that the detecting and
determining step are performed as a function of applied voltage. In
yet another embodiment, the method may include generating a
magnetic field across each material sample such that the detecting
and determining step are performed as a function of magnetic field
strength.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic drawing of an apparatus for rapidly screening
members of a combinatorial library in accordance with the present
invention.
FIG. 2a is a side view of a sample block for holding the members of
the combinatorial library.
FIG. 2b is a top view of the sample block of FIG. 2a.
FIG. 3 is a perspective view of a light source support plate and a
polarizer.
FIG. 4a is a top view of a collimator block.
FIG. 4b is a side view of the collimator block of FIG. 4a.
FIG. 5 is a perspective view of a first fiber optic plate and an
analyzer.
FIG. 6 is a top view of a second fiber optic plate.
FIG. 7a is a top view of a temperature controlled block.
FIG. 7b is a side view of the temperature controlled block of FIG.
7a.
FIGS. 8a is a top view of an alternative embodiment of the
temperature controlled block.
FIG. 8b is a side view of the alternative embodiment of the
temperature controlled block of FIG. 8a.
FIG. 9 is a schematic drawing of a substantially gas-tight
environmental chamber with the sample block mounted therein.
FIG. 10 is a cutaway of an alternative embodiment of the sample
block having electrode pairs embedded therein.
FIG. 11a is a schematic drawing of a solenoid device.
FIG. 11b is a cutaway of another embodiment of the sample block
with pairs of the solenoid devices of FIG. 11 incorporated
therein.
FIG. 12 is a schematic drawing of another embodiment of the
apparatus incorporating a pair of circular wire coils.
FIGS. 13-16 are negative images of the array of materials captured
by a CDD camera at differing temperature intervals.
FIGS. 17-18 are graphical representations of the intensity readings
of the array of materials as a function of temperature.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Overview of a Depolarized Light Scattering Array Apparatus
The present invention provides an apparatus and method for
screening an array of material samples in a combinatorial library.
Rapid screening is achieved by passing polarized light first
through the compounds or materials being characterized and then
through a polarizing filter, and measuring changes in the intensity
of the transmitted light as a function of time and/or environmental
conditions. The apparatus of the present invention allows for
screening to be done simultaneously, in parallel, for two or more
library material samples or to be carried out in a rapid serial
manner or a combination of the two. Among other benefits, changes
in the intensity of the transmitted light indicate changes in the
optical characteristics of a material. The changes are generally
associated with one or more structural transformations such as the
melting, formation, or annealing of crystallites; the relaxation of
stress-induced deformations; molecular alignment or randomization;
or transitions between different crystalline or liquid crystalline
arrangements of the molecules of a material. Such transformations
may be driven by changes in material composition, as when volatile
components of a given compound are driven off by heating above a
certain temperature; by changes in environmental conditions such as
temperature, pressure, or local electric field strength; or by
acceleration of kinetically constrained processes such as, without
limitation, the relaxation of a mechanically stressed polymer film
upon heating above its glass transition temperature. Thus, the
present invention may be used to monitor structural, kinetic, and
thermodynamic characteristics of an array of material samples, or
to identify materials desirable for a specific application.
In principle, the number of material samples which can be measured
in parallel is restricted by the number of independent measurement
channels available. This can exceed 200,000 for inexpensive,
commercially available CCD cameras. However, in practice, the
number of material samples is limited to the number of samples
which can be prepared in a reasonable amount of time for a single
set of measurements, and by the physical dimensions of the device.
Typical arrays contain between 10 and 1000 samples.
In materials where the transformations or relaxations of interest
are slow (e,g, polymers), the minimum measurement time is typically
set by the time required for the samples to achieve equilibrium at
a given set of environmental conditions (temperature, pressure,
etc.) Such values generally range from 5 to greater than 15
minutes, resulting in an effective throughput in the order of 60
samples/hr for ten measurements of an array of 100 elements. In the
absence of such kinetic retardation, the measurement time is
frequently set by the speed at which sufficiently large
environmental changes can be produced. Typical thermal ramp rates
range from 0.5 to 10.degree. C./min; measurement at 1 degree
intervals yields throughputs on the order of 1200 samples/hr.
Comparable performance can be obtained when varying pressure or gas
composition. Although local electric and magnetic fields can be
varied at much higher frequencies, measurement will be limited in
practice by the speed with which samples can be prepared and loaded
into the apparatus, effectively constraining the sampling rate to
less that 2000 samples/hr.
To perform such measurements describer above, FIG. 1 illustrates a
first embodiment of an assembled depolarized light scattering
apparatus 100 according to the present invention. Apparatus 100
includes a sample block 102 for receiving material samples for a
combinatorial library, a light source 104, at least one polarizer
(not shown in FIG. 1) and a detector 108 for obtaining light
intensity measurements. As more clearly seen in FIGS. 2a and 2b,
sample block 102 includes a plurality of predefined regions 110 in
the form of openings, illustrated by way of example as generally
circular, wherein the number of regions 110 correspond to the
number of material samples that may be used with apparatus 100 at
one time. Regions 110 are arranged in rows 112 equally spaced apart
at a predetermined distance. Each region 110 extends from a top
surface 114 to a bottom surface 116 of sample block 102 so as to
completely extend through sample block 102. At top surface 114,
regions 110 have a first diameter d.sub.1, while at bottom surface
116, regions 110 have a second diameter d.sub.2, wherein diameter
d.sub.1 >d.sub.2 so as to form a ledge 118. Ledge 118 serves as
a support for holding the bottom surfaces of vials (not shown)
containing the material samples in the combinatorial library.
Preferably, the vials are transparent to light of a predetermined
wavelength, to be explained further in greater detail. The vials
have a diameter that is slightly smaller than first diameter
d.sub.1 portion, but greater than second diameter d.sub.2 portion
such that the vials fit securely within regions 110. Further, the
length of the first diameter d, portion is substantially greater
than the length of the second diameter d.sub.2 portion and
approximately equal to the length of vials such that the vials are
fully seated within regions 110 in sample block 102, thereby
minimizing temperature variations throughout the vial, as detailed
below. To enable easy removal of the vials, preferably an upper
portion of the vials extend slightly above top surface 114 of
sample block 102. Sample block 102 is constructed of aluminum or
other suitable material.
Light source 104, which serves to provide at least one linearly
polarized light beam, is positioned adjacent to the bottom surface
116 of sample block 102 such that light is directed to pass through
at least one predefined region 110. Light source 104 may consist of
one or more sources of unpolarized light in combination with a
polarizing optical element, such as a light bulb and a sheet of
polarizing film, or of a source of inherently polarized light, such
as a laser or laser diode.
In one embodiment, light source 104 includes a plurality of light
emitting diodes (LEDs), or other suitable light sources, such as
lamps, that are adapted to simultaneously provide light beams
having a narrow distribution of wavelengths. While the use of LEDs
are preferred due to their low cost, low power consumption and the
high intensity of the resulting light beam, it is understood that
light source 104 need not be monochromatic. The use of other
suitable light sources, such as lasers is also within the scope of
this invention. However, if light source 104 only emits a single
light beam and the illumination area covered by the light beam is
less than the area of the array of material samples, an optical
element, such as a fiber optic assembly, a combination of lenses,
or a combination of lenses and mirrors must be used to divide the
light beam among the material samples of the array, such that the
entire array may be simultaneously illuminated.
The LEDs are disposed in apertures 120 along rows 122 on a support
plate 124, as seen in FIG. 3. Preferably, support plate 124 is
constructed of plastic, to reduce manufacturing costs, although
other suitable materials may be used. Further, support plate 124 is
preferably a dark color, such as black, to reduce the occurrence of
stray light scattering off support plate 124. Rows 122 correspond
to rows 112 such that the LEDs are positioned so as to be
substantially in alignment with regions 110, whereby the light
beams are directed to pass simultaneously through the vials holding
the material samples of the combinatorial library. To polarize the
light beams emitted from the LEDs, a polarizing optical element
("polarizer") 126, is placed on a top surface 128 of support plate
124 containing the LEDs wherein polarizer 126 transmits only that
portion of the light which has a specific linear polarization.
Alternatively, polarizer 126 may be a polarizing mirror (not
shown). However, to incorporate a polarizing mirror into the
apparatus, due to the angle at which the light beams must reflect
from the mirror for polarization to occur (Brewster's angle), the
relative positions of the light source, mirror, and sample block
must be altered such that the reflected beam passes through the
sample block.
Polarizer 126 polarizes the light beams before the light beams
reach the vials of material samples, thus illuminating the material
samples with focused linearly polarized light beams. The linearly
polarized light beams have a predetermined wavelength that permits
the light beams to pass through the vials and reach the material
samples. As the polarized light beams are directed toward the
material samples, they are partially collimated by their passage
through apertures 120 of support plate 124 and apertures 110 in
bottom surface 116 of sample block 102. Depending on the material
samples' optical characteristics, which may be a function of
factors such as composition or structure, the light beams are
partially depolarized after passing through the material
samples.
In accordance with one aspect of the invention, apparatus 100
further includes a collimator block 130, as seen in FIGS. 4a and
4b. Collimator block 130 is adapted to be placed on top surface 114
of sample block 102 to collimate the light beams that have passed
through the material samples, thereby reducing the occurrence of
stray light. Collimator block 130 includes a plurality of apertures
132 arranged in rows 134 defined in the block and extending
therethrough, wherein the positioning of apertures 132 correspond
to positioning of regions 110. A bottom surface 136 of collimator
block 130 includes a plurality of trough sections 138. Trough
sections 138 are formed along each row 134 and have a width that is
greater than the diameter of apertures 132. Trough sections 138 are
preferred to permit the vial tops to extend into collimator block
130, such that the collimator block rests on upper surface 114 of
sample block 102, as opposed to the top portion of the vials,
because walls of vials that are relatively thin may break under the
weight of collimator block 130. Trough sections 138 further serve
to aid in properly aligning the vials and apertures 132 of
collimator block 130. The differences in the width and the diameter
of apertures 132 and trough sections 138 result in a lip 140. Lip
140 improves the degree of collimation.
In accordance with another aspect of the invention, as shown in
FIG. 1, a second sheet of linearly polarizing material ("analyzer")
142, such as a commercially available polarizing filter, is
positioned adjacent top surface 114 of collimator block 130.
Alternatively, a mirror may be positioned adjacent to the top
surface 114 and so aligned that the light which passes through the
collimator block 130 strikes the mirror surface at the polarizing
angle (Brewster's angle). Preferably, analyzer 142 is spaced away
from collimator block 130, which will be explained in further
detail below. Analyzer 142 serves to block out any transmitted
light beams that have the same polarization direction as the
incident polarized light beams originating from light source 104,
preferably allowing only depolarized light to pass through. For
measurements of materials that undergo substantial changes in their
optical characteristics, it is preferred that analyzer 142 has the
polarization direction oriented at 90.degree. with respect to
polarizer 126, thereby, preferably resulting in complete blockage
of the transmitted light if no depolarization occurs as the light
beams pass through the samples. However, it is understood that
apparatus 100 will still operate for other, non-zero relative
orientations, such that some fraction of the incident light will be
transmitted through analyzer 142 even in the absence of any
depolarization.
Referring to FIG. 1, a detector 108 is positioned adjacent to
analyzer 142 to capture the intensity readings from the depolarized
scattered light beams and to output a signal corresponding to the
intensity of the light beams as a function of time. In this manner,
the intensity readings of the samples may be compared to ascertain
specific desirable characteristics. Detector 108 can include one or
more non-imaging optical sensors, such as semiconductor
photodetectors or photomultipliers, or an imaging system such as
the human eye, film or a charge-coupled device (CCD). In accordance
with this aspect of the invention, the preferred detector 108
includes the CCD to capture all of the intensity readings of the
material samples, as seen in FIG. 1. The CCD has a lens 144 that
focuses the light as it enters detector 108. However, due to the
narrow field of view of lens 144, to capture the intensity readings
of the material samples simultaneously, detector 108 must be
positioned a great distance from analyzer 108. As the distance
between detector 108 and analyzer 108 is increased, the sensitivity
of the readings captured by detector is decreased.
Preferably, to reduce the dimensions of the region over which the
light transmitted through the analyzer is distributed, detector 108
further includes an optical system such as fiber optic system 148.
Fiber optic system 148 includes a first fiber optic plate 150, a
second fiber optic plate 152 and fiber optic transmission media
such as a plurality of fiber optic bundles (not shown). Preferably,
fiber optic plates 150 and 152 are constructed of a dark plastic,
preferably black, so as to be non-reflective and cost efficient to
manufacture. As seen in FIG. 5, first fiber optic plate 150, which
is positioned on a top surface of analyzer 142, includes an array
of apertures 154 that are arranged a predetermined distance apart
in rows 156 that correspond to rows 112 such that, in operation,
the vials of material samples will be in substantial alignment with
apertures 154. Second fiber optic plate 152, as seen in FIG. 6,
also includes an array of apertures 158. Apertures 158 are arranged
a predetermined distance apart so as to be closely packed together
such that an overall dimension of the region of apertures 158 is
reduced relative to the overall dimension of the region of
apertures 154 of first fiber optic plate 150.
Positioned between first fiber optic plate 150 and second fiber
optic plate 152 are the plurality of fiber optic bundles (not
shown). The fiber optic bundles are connected at either end to the
first and second fiber optic plates 150 and 152 at the respective
holes 154, 156 and are in communication between first and second
fiber optic plates 150 and 152. Fiber optic plates 150 and 152
cooperate with the fiber optic bundle to reduce the size of the
area of transmitted light intensities, thereby enabling detector
108 to be positioned in close proximity with the remainder of
apparatus 100, while permitting simultaneous scanning and
characterizing of the entire array of material samples.
Alternatively, a combination of lenses or a combination of lenses
and mirrors may be used.
When the apparatus 100 is used to characterize material samples
that produce only weak depolarization of an initially linearly
polarized light beam it is preferred that apparatus 100 includes an
optical filter 157 (shown in phantom in FIG. 1) such as a
quarter-wave plate. Optical filter 157 is positioned between
polarizer 126 and sample block 102, such that the linearly
polarized light beams from light source 104 must pass through
optical filter 157 prior to reaching the material samples in sample
block 102. The optical filter 157 preferably converts linearly
polarized light into circularly polarized light. When the
circularly polarized light is transmitted through the material
samples and analyzer 142, the intensity of the light beam is
maximally dependent upon the optical characteristics of the
material sample, thereby making it possible to detect very small
changes in intensity for those materials that exhibit weak
depolarization characteristics.
Screening Device for Effects of Temperature
In accordance with another aspect of the invention, apparatus 100
may further include a temperature controlled block 159 positioned
between polarizer 126 and analyzer 142. Block 159 can be adapted to
heat or cool the array of material samples to achieve a desired
result. For example, the block can be adapted to heat or cool
during characterization such that detector 108 captures the
intensity of the depolarized light beams and outputs a signal
corresponding to the intensity of the light beams as a function of
temperature, or as a function of time at a given temperature. In a
preferred embodiment, block 159 is constructed of aluminum or other
suitable material. Referring to FIGS. 7a and 7b, block 159 includes
a well 160 having a size and shape that corresponds to the size and
shape of sample block 102 such that sample block 102 may be
positioned within well 160. Corners 162 of well 160 are preferably
radiused so as to permit easy insertion of sample block 102 within
well 160.
A bottom surface 163 of well 160 includes a plurality of apertures
164 that are arranged in rows 166, wherein the position of
apertures 164 correspond to the positions of regions 110 in sample
block 102 such that when sample block 102 is positioned in well
160, apertures 164 are in general alignment with regions 110 in
sample block 102. Apertures 164 cooperate with support plate
apertures 120 regions 110 in sample block 102 to collimate the
linearly polarized light beams as they pass through support plate
124, sample block 102 and block 159. Block 159 is either anodized,
if aluminum, or otherwise coated in black to render it
substantially non-reflective, further reducing scattered light
occurrence.
In a first embodiment, temperature controlled block 159 includes an
array of channels 168 disposed below bottom surface 163 of well
160, between rows 166. Channels 168 extend laterally through block
159 and are adapted to receive resistance heaters or thermoelectric
devices (not shown). Preferably, the temperature of the resistance
heaters or thermoelectric devices is controlled by an external
processor (not shown), although other suitable devices may be
employed. The external processor monitors a signal from a
monitoring device such as a thermocouple, thermistor or resistive
thermal device (RTD) (not shown), positioned in a small channel 174
in approximately the center of block 159. The power supplied to the
resistance heaters or thermoelectric devices is adjusted in
response to the signal received from the monitoring device.
In another alternative embodiment, referring to FIGS. 8a and 8b,
temperature-controlled block 159a may include both passages 175
carrying temperature agents and either channels 168a for resistance
heaters or thermoelectric devices mounted to a surface of
temperature controlled block 159a, wherein the temperature agents
and resistance heaters or thermoelectric devices work in
combination to vary the temperature of temperature-controlled block
159a. Similar to channels 168, passages 175 are disposed below
bottom surface 163a of well 160a and between rows 166a. However,
passages 175 are adapted to receive a liquid temperature agent (not
shown) to vary the temperature of temperature controlled block
159a. Suitable temperature agents (which may be heated or cooled)
include water, silicone oil or fluorinated solvent. Other suitable
temperature agents may also be employed. In one embodiment, to
ensure proper temperature control of temperature controlled block
159a, passages 175 extend both in a lateral and horizontal
direction so as to extend around the perimeter of block 159a and
between rows 166a. Entrance and exit ports 177 of the passages 175
are preferably threaded so as to permit easy assembly of tubing to
a separate temperature agent reservoir.
In another embodiment, temperature controlled block 159a may
include both channels 168a for resistance heaters and passages 175
carrying temperature agents working in combination to vary the
temperature of temperature controlled block 159.
Screening Device for Effects of Pressure and Environment
Composition
Referring to FIG. 9, in accordance with another aspect of the
invention, apparatus 100 may include at least one environmental
chamber 178, preferably gas tight, positioned between polarizer 126
and analyzer 142. Sample block 102 is mounted within chamber 178.
Both the upper and lower surfaces of chamber 178 are provided with
optically transparent windows 180 to permit the light beams to
reach the material samples within sample block 102 and pass through
to analyzer 142. Chamber 178 is pressurized by at least one gas
which is directed into chamber 178 through a conduit 182, or other
suitable passageway. A pressure sensor 184 working in combination
with an external processor (not shown) operates a servomechanically
actuated regulator valve 186 or piston to control the pressure of
substantially gas-tight environmental chamber 178. Detector 108
captures the depolarization data and outputs a signal corresponding
to the data as a function of pressure, or of time at a given
pressure.
In another embodiment, the chamber 178 is continuously filled with
a mixture of two or more gases. In this embodiment, additional
conduits 188 and servomechanically actuated regulator valves 190
are provided to control the flow of the gases into chamber 178. An
external processor (not shown) serves to operate regulator valves
190. Alternatively, the gases may be mixed in a separate chamber
(not shown), wherein the amounts of each gas being directed into
the chamber is controlled by separate regulator valves. Once the
gases are mixed they are then transported from the separate chamber
via conduit 182 into chamber 178. A calibrated vent valve 192 is
also included on chamber 178 to continuously permit a predetermined
amount of the mixture to be vented from chamber 178. Detector 108,
positioned on top of analyzer 142, captures depolarization data
generated from the light beams passing through the material samples
and analyzer and outputs a signal corresponding to the data as a
function of gas composition, or of time at a specific gas
composition.
In another embodiment, sample block 102 may be subdivided into a
plurality of sealed zones (not shown), wherein each zone has at
least one material sample disposed therein. Each zone would receive
a separate gas, gas mixture, or pressure. Alternatively, each
material sample may be sealed in a transparent vessel (not shown)
wherein the pressure inside each vessel is changed by varying the
temperature of the vessel.
Screening Device for Sensitivity of Electric Fields
In accordance with another aspect of the invention, FIG. 10 shows a
cut-away portion of sample block 102a, where sample block 102a
includes pairs of electrodes 194 embedded therein. Each pair of
electrodes 194 are arranged in an opposing manner with a single
region 110 positioned therebetween. Electrodes 194 are connected in
parallel to a power supply 196, such that application of voltage
across the pairs generates an electric field across each material
sample. The electric field orients molecules or supramolecular
assemblies within the material sample, thereby producing a change
in the depolarization characteristics of the material samples.
Detector 108 captures depolarization data of the material samples
and outputs a signal corresponding to the data as a function of
electric field strength, or as a function of time after the
electric field is applied or removed, or as a function of the
frequency of an alternating electric field.
When scanning the material samples as a function of voltage,
preferably the sample block is a planar sheet of glass 102a upon
which material samples are deposited. An array of electrode pairs
is arranged on glass 102a to permit generation of high electric
fields at only modest levels of applied voltage.
Screening Device for Sensitivity of Magnetic Fields
In accordance with another aspect of the invention, sample block
102b may further include a means of generating a magnetic field
which surrounds each sample. In the preferred embodiment, sample
block 102b further includes pairs of solenoids 197. Solenoids 197
are electromagnetic devices which generate a strong magnetic field
when an electric current passes through them. As seen in FIG. 11a,
solenoids 197 typically include a wire coil 198 wrapped around a
solid core 200 made of a material having a high magnetic
susceptibility such as soft iron.
Referring to FIG. 11b, each solenoid pair 197 is arranged in an
opposing manner with a single region 110 receiving a vial
containing a material sample positioned therebetween. Solenoids 197
are connected in parallel to a power supply 202, such that
application of an electric current across the pairs generate a
magnetic field across each material sample. The magnetic field
couples to the magnetic moment of molecules or supramolecular
assemblies within the material sample, thereby orienting them with
respect to the field and producing a change in the depolarizing
characteristics of the material sample. Detector 108 captures
depolarization data of the material samples and outputs a signal
corresponding to the data as a function of magnetic field strength,
or as a function of time after the magnetic field is applied or
removed, or as a function of the frequency of an alternating
magnetic field.
Alternatively, the magnetic field may be generated by surrounding
light source 104, polarizer 126, sample block 102a, analyzer 142
and fiber optic system 148 with a pair of circular wire coils 205
(i.e., Helmholz coils), as seen in FIG. 12, through which a current
is passed. Wire coils 205 generate a relatively weak but spatially
uniform magnetic field over the entire apparatus 100. In cases
where it is desired to generate an extremely high magnetic field
strength, apparatus 100 may be surrounded by one or more
electromagnets (not shown). However, in both of these embodiments,
the sample block must be constructed of a nonmagnetic (and
preferably non-conducting, in order to facilitate measurements with
alternating magnetic fields) material.
Assembly of Depolarized Scattering Light Array
Apparatus 100 is assembled so as to have all of the components
arranged in series. As such, support plate 124, collimator block
130, first fiber optic plate 150 and second fiber optic plate 152
are all provided with connector holes 204 at their respective
corners that are adapted to receive connector rods 206, as seen in
FIG. 1. Starting with the bottom, apparatus 100 is assembled such
that support plate 124 supporting light source 104 is in the first
position with light source 104 simultaneously emitting a plurality
of light beams upwardly in a linear direction to simultaneously
illuminate the entire array of material samples. The polarizer 106
is placed on top surface 128 of support plate 124 to polarize the
emitted light beams from light source 104.
Sample block 102, 102a or 102b, holding vials of material samples
to be characterized in regions 110, is positioned above and in the
path of the light beams emitted by light source 104 such that the
polarized light beams are directed to pass through the material
samples. Sample block 102 may be disposed in well 160 of
temperature controlled block 159 and mounted in environmental
chamber 178. Alternatively, sample block 102a or 102b is positioned
alone above polarizer 106. In the preferred embodiment, sample
block 102 is either anodized, if aluminum, or has a black outer
surface to render it substantially non-reflective, thereby reducing
scattered light occurrence. Next, collimator block 130 is placed on
top surface 114 of sample block 102 to collimate the polarized
light beams that are directed through the array of material
samples. In one embodiment, collimator block 130 is constructed of
polytetrafluoroethylene (e.g., TEFLON.TM.), and painted black to
reduced stray light from scattering inside the collimator block
130. TEFLON.TM. is preferred for its high melting temperature,
thereby enabling collimator block 130 to rest directly on a heated
vial block 102. Further, TEFLON.TM. is a poor thermal conductor,
thereby keeping analyzer 142 from melting and losing its polarizing
ability. Other plastics having similar characteristics, such as
ployimide (e.g., without limitation, Kapton.TM.), may be employed
in a similar manner.
The analyzer 142, having a polarizing direction oriented, in one
embodiment, at 90.degree. to filter out any transmitted light that
has the same polarization direction as the incident light beams, is
placed above collimator block 130. Preferably analyzer 142 is
spaced away from collimator block 130 a predetermined distance so
as to produce an air gap between collimator block 130 and analyzer
142 when temperature controlled block 159, is used to heat vial
block 102, as the heat would soften analyzer 142, causing loss of
polarizing ability. The air gap may also serve as additional
thermal insulation.
Next, first fiber optic plate 150 is placed on a top surface of
analyzer 142 and second fiber optic plate 152 is placed spaced
apart from and above first fiber optic plate 150. A plurality of
fiber optic bundles are arranged in a tapered configuration between
first fiber optic plate 150 and second fiber optic plate 152 to
reduce the dimension of the area of transmitted light intensities.
A detector 108, such as a CCD camera, is placed above second fiber
optic plate 152 to simultaneously capture intensity readings from
the entire array of material samples. Preferably, detector 108 is
in communication with a data storage device (not shown) to permit
analysis of the intensity readings.
Depolarized Scattering Method for Characterizing an Array of
Materials
To screen and characterize the array of material samples, the
material samples are provided in vials in regions 110 on sample
block 102, 102a or are placed on a top surface of sample block 102b
at regions 110. At least one material sample of the array is
illuminated with a linearly polarized light beam having a
predetermined wavelength. The vials in sample block 102, 102a, and
sample block 102b are transparent to the predetermined wavelength
of the light beam such that the light beam is permitted to pass
through to the material sample. The light beam is modified after it
passes through the material sample by passing the polarized light
through an analyzer 142 that has a polarizing direction preferably
oriented at 90.degree. with respect to the polarizing direction of
the linearly polarized light beam so as to completely filter out
light intensities having the same polarization direction as the
incident light beam. Next, changes in the intensity of the light
beam due to changes in the optical characteristics of the material
samples are detected and characteristics of the material sample are
determined based on the intensity readings as a function of
time.
In the preferred method, the step of illuminating the material
sample includes providing a light source 104 that comprises a
plurality of LEDs that simultaneously emit a plurality of light
beams which are passed through a polarizer 126 so as to produce
linearly polarized light beams. The linearly polarized light beams
simultaneously illuminate the entire array of material samples.
After the polarized light beams pass through the array, the beams
are then collimated prior to being directed through the analyzer
142.
In an alternative method, the light beams are converted to
circularly polarized light by passing the linearly polarized light
beams through an optical filter 157 prior to reaching to material
samples. The circularly polarized light permits scanning and
characterizing of material samples that produce weakly polarized
light beam intensities when subjected to linearly polarized light
beams.
In accordance with another aspect of the invention, the detecting
and determining step of the method includes collecting readings of
the changes of light intensity of the light beams that pass through
the array of material samples. After the intensity of the polarized
light beams are filtered by the analyzer 142, the changes in
intensity values are passed through a first fiber optic plate 150.
Fiber optic bundles extending from first fiber optic plate 150 are
connected to a second fiber optic plate 152 in a tapered
configuration to reduce the area of transmitted light intensities
such that intensity readings of the material samples may be
captured simultaneously. A CCD camera is then provided to capture
the intensity readings at predetermined time intervals, wherein the
intensity readings provide information on the characteristics of
the array of materials.
In accordance with another aspect of the invention, the method may
further include the step of varying the temperature of the array of
material samples at a predefined rate. This step is accomplished by
placing sample block 102 into the temperature controlled block 159.
As such, the determining step may be performed as a function of
temperature or, alternatively, the material samples are heated or
cooled to a fixed temperature and the changes in intensity are
detected as a function of time.
In accordance with another aspect of the invention, the method may
further include subjecting the material samples to pressure by
enclosing the material sample in the environmental chamber 178 and
filling chamber 178 with at least one gas. As such, the determining
step may be performed as a function of pressure.
In accordance with another aspect of the invention, the method may
further include continuously subjecting the material sample to a
mixture to two or more gases. This step is accomplished by
enclosing the material sample within the environmental chamber 178
and continuously filling the chamber 178 with the mixture of two or
more gases. The mixture is vented from the chamber 178 at a
predetermined rate. The determining step may be performed as a
function of gas composition.
In accordance with another aspect of the invention, the method may
further include the step of generating an electric field across
each material sample. The electric field orients the molecular of
the material samples or any supramolecular assemblies within the
material samples, thereby changing the depolarization structure of
the material samples. The determining step is then able to be
performed as a function of electric field strength, as a function
of time after the electric field is applied or removed, or as a
function of the frequency of a alternating electric field.
In accordance with another aspect of the invention, the method may
include the step of generating a magnetic field across each
material sample. The magnetic field couples to the magnetic moment
of molecules or supramolecular assemblies within the material
sample, thereby orientating the assemblies with respect to the
magenetic field and producing a change in the depolarizing
characteristics of the material sample. The determining step is
then able to be performed as a function of magnetic field
strength.
EXAMPLE
The following example is intended as illustrative and non-limiting,
and represent specific embodiments of the present invention.
Referring to FIGS. 13-18, to demonstrate depolarized scattering
using an embodiment of the disclosed apparatus and method, the
results of the characterization of a series of commercially
available materials from Aldrich Chemical Company will be
discussed. The materials consist of ethylene copolymerized with
either methyl aerylate (MA) or vinyl acetate (VA) The
characteristics of the copolymers, as reported by the supplier,
appear below, in Table 1.
TABLE 1 ______________________________________ Melting Temperatures
for Polyethylene Copolymers Region Comonomer Melting Point
(.degree. C.) ______________________________________ H4 12 wt % VA
95 G2 6.5 wt % MA 106 E2 18 wt % VA 87 D4 9 wt % MA 93 C2 25 wt %
VA 75 ______________________________________
Approximately 60 mg of the copolymers are individually provided in
flat-bottom glass vials 6 mm in inner diameter with wall thickness
of 1 mm. At low temperatures, all of these materials exhibit a
birefringent morphology that includes crystalline polyethylene
domains in a matrix of ethylene and either vinyl acetate or methyl
acrylate segments. Upon heating above the melting point of the
cystalline domains, the sample forms a spatially isotropic liquid
and the birefringence disappears.
Once the material samples are placed in the vials, the vials are
heated on a hot plate to about 140.degree. C. to eliminate
birefringent stresses associated with processing the material
samples. The resulting material, in liquid form, adopts the shape
of the vials, thereby forming a uniform plug approximately 2 mm in
height. The vials are then removed from the hot plate and cooled to
room temperature.
Once cooled, the vials are placed in regions 110 in sample block
102 and sample block 102 is positioned within the temperature
controlled block 159. The light source 104 is directed at the
material samples. The temperature controlled block 159 is then
heated from about 70 to 120.degree. C. at a rate of about
1.0.degree. C./min. The intensity of the depolarized light beams
transmitted through the vials is captured every two minutes by a
lens-coupled CCD camera using an exposure time of 15 ms.
The resulting images captured by the CCD camera are shown in FIGS.
13-16. FIG. 13 is a negative image of the array of material samples
at 70.degree. C. with a linear grayscale. Regions B4, C2, D4, E2,
F4, G2 and H4 contain samples. All other regions are empty.
FIG. 14 is a negative image recorded at about 86.degree. C. upon
heating at about 1 .degree. C/min. As can be seen, regions C2 and
F2 show a marked drop in intensity relative to the 70.degree. C.
image.
Referring to FIG. 15, at 102.degree. C., only D4 and G2 exhibit a
notable signal. However, upon reaching 116.degree. C., all of the
depolarization associated with the material samples has
disappeared, indicating that all of the crystallites have melted,
as can be seen in FIG. 16.
After the images of the material samples are captured by the CCD,
the images can be digitized and analyzed, such as by suitable
software. Graphical representations of the intensity data as a
function of temperature are set out in FIGS. 17 and 18. Referring
to FIG. 17, the temperature dependence of the transmitted intensity
for regions G2 (6.5 wt % methyl acrylate) and D4 (9.0 wt % methyl
acrylate) are shown. For comparison, the intensity data for empty
region F2 is also shown. For the VA copolymers, the measured
transition temperature for the 6.5 wt % material sample corresponds
to the value supplied by the supplier, as seen in Table 1. However,
the value for the 9 wt % material sample is approximately ten
degrees less than the value reported in Table 1. This discrepency
may reflect the presence of two different populations of
cystallites. This hypothesis is supported by the differing slopes
in the transition region (90-98.degree. C. and 98-106.degree. C.,
respectively).
Referring to FIG. 18, the measured temperature dependence of the
total intensity measured for regions H4 (12 wt % vinyl acetate), E2
(18 wt % vinyl acetate) and C2 (25 wt % vinyl acetate) of MA
copolymers are depicted. The melting point is experimentally
defined as the midpoint of the range in which the measured signal
drops from the low-temperature value (approximated by a straight
line) to the high-temperature value (also approximated by a
straight line). Melting points identified in this manner generally
correspond to the values reported by the supplier in Table 1,
within a few degrees. This discrepancy is comparable to that
associated with the thermal gradients within the system. Further,
the discrepancy may also reflect the use of a different heating
rate as compared to the supplier's heating rate.
Preferred embodiments of the present invention have been disclosed.
A person of ordinary skill in the art would realize, however, that
certain modifications would come within the teachings of this
invention. Therefore, the following claims should be studied to
determine the true scope and content of the invention.
* * * * *